Equilibrator



J. F. JOY

EQUILIBRAT'OR Jan. 8, 1946.

Filed March 43, 1942 Patented Jan. 8, 1946 UNITED STATES PATENT OFFICE EQUILIBRATOR Joseph F. Joy, Claremont, N. H.

Application March 3, 1942, Serial No. 433,139

(C1. 2cv-1) (Granted under the act of March .3, lass, as

amended April 30, 1928; .370 0. G. 7.57)

7 Claims.

The invention described herein may be manufactured 4and used by or for the Government for governmental purposes, without the payment to :ne of any royalty thereon.

This invention relates to a hydro-pneumatic device and more particularly to `a hydropneumatic equilibrator intended to balance the weight of heavy mechanisms such as artillery weapons.

In devices of this character it is desirable that a liquid pressure transmitting medium be used which may perform the additional functions of lubricating the cylinder walls and facilitating the packing or sealing of piston and piston rod. It is also desirable that some compressed gaseous medium be provided to absorb and balance the loads applied to the pressure transmitting medium. At the same time to avoid undesirable absorption of gas in the liquid medium a sep.- aration should be maintained between the liquid and gaseous media While providing for a free exchange of pressure therebetween.

It is therefore an object of this invention to provide a hydro-pneumatic equilibrator in which a practically frictionless separation may be maintained between liquid and gas.

It is a further object to provide an equilibrator of the character discussed above which may be conveniently and economically manufactured.

It is another object to provide an equilibrator having substantially frictionless separating means between the liquid and gas which will be immune to damage in the event of the leakage of any considerable quantity of the liquid medium.

The exact nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawing in which:

Fig. l is a longitudinal sectional View of an equilibrator constructed according to my invention and shown in retracted position.

Fig. 2 is a similar view on a reduced scale show ing the equilibrator in fully extended position.

Figure 3 is a cross sectional view on the line 3-3 of Fig. 1.

Figure 4 is a similar view on the line 4 of Fig. 2.

Referring to the drawing by characters of reference there is shown a main cylinder I having within and concentric therewith a second cylinder 2 of less length than the cylinder I. A cylinder head 3 is provided with an internally threaded portion 4 adapted to be secured to the end of the cylinder 2 and to act as a support and closure therefor. A portion 5 of the head 3 is provided with a shoulder i and external threads adapted to engage lthe end of the main cylinder I. A passage -I formed through the head 3 communicates with the space between the cylinders i and 2 and an air valve 8 is provided at the outer end of the passage 1. A fitting 9 may be provided on the cylinder head to enable the equilibrator to be attached to the device to be balanced. A centrally apertured diaphragm I0, received within the cylinder I and having grooves II in its cylinder engaging portion, is provided with an internally threaded portion l2 adapted to engage the inner end of the cylinder 2. A piston I3 slidable in the cylinder 2 is provided with packing I 4 which may be retained by a packing nut I5. A `piston rod I6 is secured to the piston and extends beyond the opposite end of the cylinder I. A cylinder head I'I is provided for the last mentioned end of the cylinder I and has formed therein a centrally located aperture for the passage of the piston rod I 6. A packing gland comprising packing I8 and a packing nut I9 prevents the escape of oil along the piston rod. A fitting 20 on the end of the piston rod may be utilized to connect the equilibrator to the device to be balanced and a bellows-like member 2I secured at one end to the fitting 2D and at the other end to the packing nut I9 surrounds the piston rod and protects its exposed portions from dust or other abrasive material. A passageway 22 is formed through the cylinder head Il and an oil `filler valve 23 vis secured therein.

A secondary cylinder head 24 has a central aperture through which the piston rod passes and may be secured in the cylinder in spaced relation to the cylinder head I7 by means of a ring 25 of rubber-like packing material compressed between the angular shoulder 26 on the secondary cylinder head and a similar shoulder 2l on a ring member 28 drawn into engagement with the packing ring by bolts 2S engaging the secondary cylinder head. Engaging internal threads in the central apertures of the secondary cylinder head 24 and the diaphragm I0 and extending therebetween is a tube 30 having a plurality of small holes 30a piercing its wall in the section between the diaphragm and secondary cylinder head. An expansible tube 3| of natural or synthetic rubber or other material having rubberlike properties surrounds the pierced tube 30 and is provided with a. bead-like ange 32 at each end. Annular channels 33 complementary in shape to the flange 32 are provided in the faces of the diaphragm -and secondary cylinder head 2. for the reception of the flanges 32. A pair of similar ilanged members 34 are secured to the diaphragm I and secondary cylinder head by means of screws and are provided with an annular portion B adapted to engage the beadlike ange 32 and compress the same into the channel 33 forming a gas and liquid tight joint. Portions 3'! and- 38. ofthe flangedmembers diverge from the expansible tube 3|. Secured to the portion 38 of one of the anged members by Welding or other convenient means and engaged over the portion 31 of the other flanged member is a metallic tube '39 provided with a plurality of small apertures 39a. f i

In the use of the equilibrator oil.0r. other convenient liquid may be introduced through the ller valve 23 preferably with the equilibrator in the position shown in Fig. 2 until the ex-YI pansible tube 3| has ben expanded and :the space therein as well as the space between the cylinder head il and the secondary cylinder head 24 have all been completely lledwith fluid and purged of imprisoned air bubbles. YThrough the valve 'air or other compressible fluid may be introduced into the main cylinder and Will surroundk the inner cylinder and expansible tube butrwill be positively separated from the liquid contained therein. Suiicient gaswill be introduced to support the unbalanced load connected to the fittings S and 2t, thus permitting the load to be moved readily in either direction with a minimum expenditure of energy. vIt will be obvious that, as the load is moved in a direction tending to extend. the equilibrator, the piston will be drawn through the cylinder and will displace the liquid contained therein through the apertures 33a in the tube Vti) to expand the expansible tube 3l against the pressure of the sur-` rounding gas. In the event o f the leakage of any considerable quantity of oil there will be no escape Vof gas and no possibility of destruction of the expansible tube as Ythe tube Willbe pressed into engagement with the tube Se and will act as a valve in closing the apertures 30a. The provision Vof a similar apertured tube exterior to the expansible member serves to protect the expansible tube by restraining bulges or other tendencies toward non-uniform expansion.

Obviously a device of this type is not limited in its utility to use as an equilibrator for a gun b ut may be used in any location requiring a resilient Vsupport in the natureof a spring the resistance of which may be conveniently regulated by the regulation of the pressure ofthe air-confined. It should be noted that the only portions of the apparatus requiring surface finishing are of simple and readily accessible form and that highly i nished surfaces have been reduced to a minipiston rod is slidable, an expandible tube of rubber-like material secured at one end to the open end of said cylinder and at the other end to said jacket in surrounding relation to said piston rod, a liquid contained in said cylinder and tube, and gas under pressure contained between said jacket and Said tube, said gas being subject to further 'compression as said piston rod is withdrawn from said cylinder.

2. In an equilibrator as described in claim 1, a perforated metallic tube inside said expandible tube and supported at the ends thereof whereby said metallic tube will support said expandible tube in .the event of leakage of fluid from said cylinder.

3. In an equilibrator as described Vin claim 1, a perforated metallic tube surrounding said expandible tube and supported at the ends thereof 1 whereby said expandible tube may be supported against any tendency to localized abnormal expansion. j

4. Anequilibrator as described in claim l, a head in the end of said cylinder remote from said open end, an enlarged rim on said cylinder head, and means by which an end of said jacket may be secured to said rim. 5. An equilibrator comprising a cylindrical jacket, closure means for an end of said jacket, a cylinder in said jacket secured to said closure means in coaxial relation with said jacket, a piston in said cylinder, a packing gland in the end of said jacket opposed to said closure means, a piston rod extending through said gland into secured relation with said piston, a centrally apertured secondary closure secured in the end of Vsaid jacket adjacent said packing, an expandible tube of rubber-like material secured at one end to said cylinder and at the other end to said secondary closure in surrounding relation to said piston rod, a liquid contained in said cylinder and the space Within said expandible tube, and a compressed gas contained in said jacket, said gas being subject to further compression as said piston is withdrawn and the expandible member is expanded by the displaced liquid.

6. An equilibratoras described in claim Band a pair of perforated metallic tubes supported in coaxial relation withsaid expandible tube, one of said perforated tubes being inside said expandible tube and one oi said perforated tubes being outside said expandible tube whereby said expandible tube may be supported against any tendency to abnormal deformation.Y

7. An equilibrator comprising a cylinder, a piston in said cylinder, a piston rod extending without the cylinder, an expandible tube of rubberlike materialfsurrounding said rod and secured to an end of vsaid cylinder, closure means for the end of said expandible tube, a packing gland in Vsaid closure means through which said piston rod is slidable, a jacket surrounding said expandible tube and secured at one en'd to said closure means and at the other end to said cylinder, compressed gas in said'jacket, and liquid in said cylinderand said expandible tube whereby said gas may be further compressed as said liquid is displaedby said piston. Y

JOSEPH F. JOY. 

